High-performance RF detector ADL5511 (ADI)

Analog Devices, Inc. (ADI) has recently launched a highly integrated, high-performance RF detector, the ADL5511, which is suitable for wireless, instrumentation, defense and other broadband applications. This new TruPwr RMS and envelope detector (an electronic circuit that takes an RF signal as input and provides a signal envelope as output) from ADI integrates two RF functions in a small chip, which not only simplifies the design, but also reduces the bill of materials cost, and achieves a high level of integration and functionality.

Improving the PAE (power added efficiency) of high power amplifiers remains a huge challenge for wireless and broadband equipment manufacturers. The new generation of WiMAX systems and LTE mobile data and voice systems are beginning to use OFDM (orthogonal frequency division multiplexing) modulation to support a large number of subcarriers. This type of modulated signal has a high peak-to-average ratio, which causes the PA (power amplifier) ​​to transmit power much lower than its maximum power, resulting in reduced PA efficiency. To improve PA efficiency, envelope detectors are becoming increasingly popular. In the drain modulation architecture, the envelope detector adjusts the PA power supply when the RF signal is input, so that the PA only provides the power required to correctly transmit the RF signal. In traditional architectures, in order to ensure that the PA can correctly transmit the peak power, the PA is biased to a high power level, but the PA bias cannot be reduced when transmitting lower RF power.

Envelope Output
Analog Devices' new TruPwr RMS and envelope detector, the ADL5511, offers a unique approach to improving PAE, operating from 1-MHz to 4-GHz in a smaller, lower-cost package that allows you to easily and accurately extract the envelope of a modulated signal. The envelope output is expressed as a voltage proportional to the envelope of the input signal. The RMS output is expressed as a linear V/V output voltage, independent of the peak-to-average ratio of the input signal. The extracted envelope can be used to improve power amplifier linearization and efficiency, while the RMS output can be used for true power measurement. The ADL5511 offers best-in-class performance, with both RMS and envelope detection accuracy of ±0.25 dB over temperature, and a dynamic range of ±1 dB at 40 dB. The ADL5511 is rated for operation over the industry's widest temperature range of –40°C to +125°C, making it ideal for use in high-temperature environments such as remote radio heads and power amplifiers.

ADL5511 is available for sampling now, priced at $7.33 per piece in 1,000-piece quantities.